Morgan Stanley said an employee stole data from up to 10 percent of its wealth management clients, including account names and numbers, but there was no evidence of economic loss.

The bank said the employee had been fired and law enforcement and regulatory authorities had been informed.

Morgan Stanley said information of about 900 clients had been briefly posted on the Internet.

The bank believes that the employee was trying to sell the data, though investigations are ongoing, according to a person familiar with the matter.

Morgan Stanley discovered the theft on Dec. 27 as part of a regular sweep of the Internet, the source added.

The stolen data does not include account passwords or social security numbers, Morgan Stanley said.

All affected clients are being contacted, the bank said.